title: Megalobrama amblycephala cardiac troponin T variants: molecular cloning, expression and response to nitrite.
abstract: Cardiac troponin T (TNNT2), as a member of troponin superfamily, plays important roles during early cardiogenesis, and contraction and relaxation of myocardial cells. In this study, two alternatively spliced variants of Megalobrama amblycephala TNNT2 were identified showing a difference of 19 amino acids in the N-terminal hypervariable region. The longer cDNA (TNNT2-1) was 1,118 bp, encoding 284 amino acid residues, contained conserved central tropomyosin-binding region, cardiac specific signal and C-terminal segments except the N-terminal hypervariable region. The TNNT2 transcripts first appeared at 16 hours post-fertilization (hpf) peaking at 28 hpf (onset of heartbeat). In addition, strong expression of TNNT2 was found in the cardiac muscle. After nitrite exposure, the increased TNNT2 expression levels in the heart indicated that nitrite might induce cardiac injury. Results of semi-quantitative RT-PCR indicated that the two alternatively spliced variants existed in early development stages since their first appearance at 16 hpf and heart, spleen, headkiney of M. amblycephala. The shorter transcript (TNNT2-2) was proved to be dominant in the embryos and heart of M. amblycephala, furthermore, the increase of TNNT2 expression level in the heart after nitrite exposure was mainly caused by TNNT2-2.
authors.affiliation: Key Lab of Freshwater Animal Breeding, Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction, Ministry of Education, College of Fisheries, Huazhong Agricultural University, 430070 Wuhan, PR China.
authors.forename: Li Ping
authors.initials: LP
authors.lastname: Chen
authors.forename: Jie
authors.initials: J
authors.lastname: Zhang
authors.forename: Xin Lan
authors.initials: XL
authors.lastname: Wei
authors.forename: Nan
authors.initials: N
authors.lastname: Chen
authors.forename: Chun Xiao
authors.initials: CX
authors.lastname: Huang
authors.forename: Meng Xia
authors.initials: MX
authors.lastname: Xu
authors.forename: Wei Min
authors.initials: WM
authors.lastname: Wang
authors.forename: Huan Ling
authors.initials: HL
authors.lastname: Wang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D003530:Cyprinidae / Q000235:genetics*; D017931:DNA Primers; D018076:DNA, Complementary; D008969:Molecular Sequence Data; D009206:Myocardium / Q000378:metabolism*; D009573:Nitrites / Q000378:metabolism*; D010802:Phylogeny; D060888:Real-Time Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D020107:Troponin T / Q000737:chemistry / Q000235:genetics*
chemical_list: D017931:DNA Primers; D018076:DNA, Complementary; D009573:Nitrites; D020107:Troponin T
keywords: Alternative splicing; Expression profiles; Megalobrama amblycephala; Nitrite exposure; TNNT1; TNNT2; TNNT2-1; TNNT2-2; TNNT3; TnT; cardiac troponin T; fast skeletal TnT; hours post-fertilization; hpf; slow skeletal TnT; the longer isoform of cardiac troponin T; the shorter isoform of cardiac troponin T; troponin T